Transmission system



Patented Jan. 23, 1934 1,944,308 TRANSMISSION SYSTEM Howard C. Turner, Amiiston,

Ala., assignor to American Telephone and Telegraph Company, a corporation of New York Application February 15, 1933. Serial No. 656,949

2 Claims.

This inventionrelates to announcing systems and particularly to those used for emergency pur- It will be described for the sake of illustration as adapted to small hotels although other 5 uses are possible and entirely within the scope of this invention.

In accordance with modern practice many hotels are equipped with an electrical system for supplying guests with radio and other forms of diverging programs. These systems generally comprise a central source of such programs, usually a radio or electric phonograph, and individual receivers in the rooms connected to the program source through suitable conductors. Each receiver is equipped with a' switch for selecting the desired program or for shutting the receiver oil entirely, according to the will of the guest. Since the circuit through a receiver may be broken at any time, general announcements to the guests can not be made through this system by the hotel management and an auxiliary system must be employed. The object of this invention is to supply a simple and inexpensive auxiliary announcing system for a program distributing system which uses a minimum or additional equipment. The means whereby this object is carried out comprise a transmitter, a switch and a separate conductor connecting the transmitter through the switch to the receivers so that control 01 the receivers may be taken from the individualreceiver switches at any time and transferred to'the emergency announcing-system.

The accompanying drawing shows two forms which this invention may take. The form shown .in Fig. 1 is used where a program distributing system is already installed and it is not expedient to change the receiver switches oi. the system to accommodate the auxiliary announcing system and the form shown in Fig. 2 may be used in new installations where the receiver switches can be conveniently changed.

In Fig. 1, 10, 11 and 12 designate receivers located at. various points in a hotel, apartment house, hospital and the like. It is understood that a greater number of receivers than is shown may be employed without afl'ecting the operation of this invention. Each receiver is supplied with .a. selector receiver switch 13, 14 and 15, respec- 5 tively, for connecting it to one of the available program sources 16 and 17. These sources may be radios, phonographs or other similar devices. They are connected to the receivers through a common return 18 and individual leads 19 and 20. The receiver switches are provided with suitable contacts for the leads 19 and 20 (designated 1 and 2 respectively) and withan off position whereby the cooperating receiver may be disconnected from the program sources if desired. A main control switch 21 is located near the auxiliary announcing station and is provided to disconnect the program sources simultaneously from all of the receivers.

The auxiliary system comprises individual leads 22, 23 and-24 connected to the receiver side of each receiver switch, a bridging switch 25, a

transmitter 26, a suitable source of energy 2'? and the commonreturn lead 18. When it is desired to make an emergency announcement; switch 21 is opened and the bridging switch 25 is closed. This puts all of the receivers into the auxiliary circuit exclusively so that nothing but the sounds actuating the transmitter 26 is heard. For normal operation switch I 21 is closed and bridging switch 25 is opened so that the receivers are again under the control of their respective receiver switches.

In the form shown in Fig. 2 the same receivers 10, 11 and 12, program sources 16 and 17, transmitter 26 and energy source 27 are used as well 30v as the common return 18 and individual program leads 19 and 20. The receiver switches, however,

are changed so that the "011 position connects the receiver to a common lead 28 which is brought down together with the program leads 19 and 20 to the poles of a multiple pole double throw switch 29. The right hand position contacts of switch 29 are bridged and connected to the energy source 27 and transmitter 26. Twoof the left hand contacts are connected to the program sources 16 w and 17 and the third is open. When it is desired to make an emergency announcement with this arrangement, switch 29.

is thrown to the right and all of the receivers are thus connected into the auxiliary circuit no matter what the position of the individual receiver switches may be at the moment. For normal operation switch 29 is thrown to the left which connects leads 19' and 20 to their respective program sources and-opens lead 28.

The advantages of the .two systemsjust described are their economy and simplicity. No additional apparatus is required except the installation of the leads for the emergency system. I1 the entire system is Just being installed this 5 is very simple and-requires practically no extra work. For the greatest economy the second form is preferable since but one extra lead is required irrespective of the number of receivers in the circuit. Still further economy may be 'efl'ected g,v

by using the amplifiers of one of the program sources for the auxiliary circuit instead of supplying a separate amplifier as shown.

What is claimed is:

1. The combination of a. program distributing system comprising 2. plursiity of receivers, a plurality of program sources, selector switches individual to each receiver comprising an 03" position and a. position for each program source, is msin control switch, and an I nesting each position of the selector switch to the main control switch, with an emergency announcing system comprising I a, transmitter, a source of energy therefor, means on the control switch for connecting the individual leads to the selector switches either to their respective program sources or to the emergency announcing station and a common return lead connecting the individual lead con-- receivers, program sources and emergency snnouncins system.

2. In a. program distributing system comprising a. plurality of receivers, a. plurality oi program sources, selector switches in proximity and individual to each receiver comprising an ofi" position and a position for each program source, a remote emergency announcing system and unitery means etthe announcing system for com meeting all oi the receivers to the snnouncins system irrespective of the position oithe selector switch, said. means comprising a switch adapted in one position to bridge the positions of the se-ev lector switches including the ofif position and in another position to connect the positions to their respective sources.

HOW C. TURNER. 

